When an MP3 (MPEG Audio Layer III) file is being decoded and played back on audio speakers in a looping pattern, there is a perceptible silence that can be heard between the end of the audio content and when the digital audio music player loops back to play the beginning of the audio content. This silence is a byproduct of the encoding process to convert an audio file into an encoded MP3 format. The original audio file is divided into equally sized frames containing 1152 samples, and then the MP3 encoder adds silence to the beginning and end of the file to make the resulting encoded MP3 file into an integer number of frames, each containing exactly 1152 samples. Even if the original audio file is evenly divisible by 1152 samples into an even number of frames, the MP3 encoding process still adds a certain amount of padding known as encoder/decoder delay. These “pads” are what prevent the MP3 file from looping seamlessly without any audibly perceptible added silence between each loop.
This silence is particularly noticeable when the MP3 files are being decoded through a web browser where no back-end software exists to “reassemble” a file so it sounds seamless from one loop to another. Adobe's FLASH encoder is platform-specific and requires the client to install a proprietary software component to play audio content. Another problem with this process is that it is not sample-locked and therefore tends to drift, thus causing audible pops and hiccups during playback.
Other solutions exist that try to create gapless looping MP3 tracks, but these solutions require software applications or plugins to be installed outside of the web browser on the client device. For example, they require extensive preparation or manipulation of the original audio file, installation of one or more utility or encoder programs, and/or multiple encoding steps. Even still, during the first playback, a gap will be present.
In some environments, having gaps of silence between looping audio playback is extremely undesirable. It is aurally distracting and can detract from the user experience. For example, in a wagering game, having a gapless looping audio sound is very important for creating an exciting multi-sensory experience, which relies on visual and audible, and sometimes haptic or tactile, cues to create an exciting and immersing environment for the player.